A valve for fluids, preferably for gases

ABSTRACT

A valve (1) for fluids, preferably for gases, comprising an inlet passage (2); an outlet passage (3); a shutter (4) interposed between the inlet passage (2) and the outlet passage (3) and movable between an open position and a closed position; actuating means (5) operatively active on the shutter (4); and a first stabilisation membrane (6) interposed between the shutter (4) and a fixed portion (7) of the valve (1). The first stabilisation membrane (6) exposes an active wall (8) to the fluid, which has an outer surface (9) shaped in such a way that the pressure of the fluid acting on the active wall (8) is lower than the pressure of the fluid acting on the rear surface (10) of the shutter (4), preventing the fluid from opening the shutter (4), when the shutter (4) is in the closed position and when the valve (1) is in a back pressure condition.

TECHNICAL FIELD

The present invention relates to a valve for fluids. In particular, thepresent valve is used for intercepting gasses at a burner, but could beused in any sector for intercepting, in general, a fluid. Moreover, thepresent invention relates to a valve of the type having one or moreconsecutive and independent stages or a single-stage valve.

PRIOR ART

Electromechanical actuators, often also defined as “solenoid valves” areelectromechanical components interposed along a pipeline to allow theinterception or the adjustment of the flow rate and/or the pressure of afluid (liquid or gaseous) of interest made to flow in the pipeline.

The management of the quantity of fluid passing through the solenoidvalve, and therefore along the pipeline, takes place through the controlof the movement of a shutter having a high operating precision thatallows the solenoid valves to also be used as safety devices.

An example of this type of device is reported in the documentsEP3070381, WO2015/111087 and WO2015/111088, in which a solenoid valve isillustrated having multiple stages cooperating for the adjustment of thequantity of gas that can be transported through the pipeline.

Solenoid valves must have certain characteristics capable of ensuring ahigh level of safety, such that they can be approved and are thereforeable to be used.

To check the possible degree of safety that they can provide in theevent of a malfunction, a specific test to which they are subjected isthe so-called “back pressure test”. In this test, the fluid in questionis made to flow from the outlet opening of the valve to the inletopening, i.e. in the opposite direction with respect to the normal useof the valve.

During the test, the shutter interposed between the accesses of thevalve must ensure a perfect seal, preventing the fluid from reaching theinlet opening.

Moreover, there are also other safety tests such as that involving theremoval of the stabilisation membrane and the entry of the gas from theinlet passage.

The increase in the safety class of solenoid valves leads to an increasein the pressure required for the back-pressure test. To overcome testswith higher pressures, therefore, it is necessary to increase theclosing force of the elements inside the valve. All this involves anincrease in the energy necessary for the activation of the operators inthe normal use of the same.

However, given the high pressure of the fluid during these tests and/orin case of a malfunction, and given the increasingly restrictivethresholds to ensure safety, in certain situations the suitability foruse is not achieved.

In fact, given the high pressure of the fluid during these tests and/orin the event of a malfunction, the shutter is subject to differentpressing forces able to move it from its closed position, with theconsequence of reducing the degree of safety offered by the valve.

OBJECT OF THE INVENTION

In this context, the technical task of the present invention is topropose a valve for fluids, preferably for gases, which obviates thedrawback of the known art as mentioned above.

In particular, the object of the present invention is to provide a valvefor fluids able to ensure a high level of safety at least during backpressure tests or with the removal of the stabilisation membrane.

The stated technical task and specified object are substantiallyachieved by a valve for fluids, preferably for gases, which comprisesthe technical features set forth in the independent claim. The dependentclaims correspond to further advantageous aspects of the invention.

It should be highlighted that this summary introduces, in simplifiedform, a selection of concepts which will be further elaborated in thedetailed description given below.

The invention relates to a valve for fluids, preferably for gases, whichcomprises an inlet passage for a fluid, an outlet passage for the fluid,a shutter interposed between these passages and movable along a movementdirection between an open position and a closed position. In the openposition the shutter allows the flow of the gas from the inlet passageto the outlet passage, while in the closed position the shutter preventsthe flow of the gas.

Furthermore, the valve for fluids comprises actuating means movablealong the movement direction and operatively active on the shutter formoving the shutter into the open position, and a first stabilisationmembrane interposed between the shutter and a fixed portion of the valvein such a way as to expose an active wall to the fluid present betweenthe outlet passage and the shutter.

Specifically, the active wall has an outer surface arranged at theoutlet passage and facing towards a rear surface of the shutter, whichis opposite the inlet passage of the valve. The outer surface isconformed so that the pressure of the fluid acting on said active wallgenerates a force that is lower than the force generated by the pressureof the fluid acting on the rear surface of the shutter, so as to preventthe pressurised fluid from being able to open the shutter when thelatter is in the closed position and the valve is at the same time in aback pressure condition, i.e. a condition in which the fluid flows fromthe outlet passage towards the inlet passage.

Advantageously, both in the case of a back pressure test and in the caseof a malfunction, the first stabilisation membrane of the valve is ableto reduce the pressure of the fluid acting on the shutter to prevent thelatter from moving into the open position, allowing the counterflow ofthe fluid.

Preferably, the actuating means extends along an axis of extensionparallel to the movement direction.

According to one aspect of the invention, the first stabilisationmembrane surrounds the axis of extension, lying on a plane substantiallyorthogonal to the axis of extension itself.

Preferably, the active wall is inclined with respect to the axis ofextension towards a common portion of the shutter.

In this way the stabilisation membrane assumes an advantageousconformation like a cone or a truncated cone, in which the protrusion ofthe outer surface of the active wall of the membrane is smaller than therear surface of the turned shutter. Consequently, this configurationprovides that the pressing forces induced by the gas on the active walland on the shutter are unbalanced in favour of the latter, keeping it inthe closed position also in the case in which the fluid flows from theoutlet passage towards the inlet passage (back pressure).

Even more preferably, the first stabilisation membrane is of the bellowstype for following the movement of the actuating means along themovement direction.

According to a different aspect of the invention, the active wall has aconcavity that extends away from the shutter substantially along themovement direction.

According to another aspect of the invention, the first stabilisationmembrane comprises a sleeve connected to the active wall and arrangedadjacent to at least part of the actuating means for being constrainedto the latter at the shutter.

Advantageously, the sleeve allows good adhesion with the actuatingmeans, in such a way that the stabilisation membrane is able to remainintegral with the actuating means itself during the movement of theshutter between the closed position and the open position.

According to one aspect of the invention, the valve comprises an elasticelement interposed between the fixed portion of the valve and theshutter for moving and/or keeping the shutter itself in the closedposition.

The elastic element, preferably a spring working in extension, allowsmoving and/or keeping the shutter in the closed position, being able toapply a pressing force directly on the rear surface of the shutter,distancing it from the stabilisation membrane.

Preferably, the first stabilisation membrane has a connecting portionarranged between the elastic element and the fixed portion.

Thanks to the presence of the elastic element, which produces pressingforces on both the shutter and on the fixed portion of the valve, it ispossible to keep the stabilisation membrane in a stable position withrespect to the fixed portion of the valve by interposing a connectingportion of the membrane directly between the fixed portion and theelastic element in tension.

According to one aspect of the invention, the valve comprises a primaryvolume defined between the inlet passage and the outlet passage, and asecondary volume arranged along the movement direction and separatedfrom the primary volume by the first stabilisation membrane.

Substantially, the primary volume identifies a first stage of the valve,while the secondary volume identifies a second stage.

Most of the fluid flows inside the primary volume and it comprises someparts of the valve, such as the shutter, elastic elements and any otherdevices that are useful for its operation. Further components arearranged in the secondary volume; this volume is arranged separately andsubstantially transverse to the primary volume.

Preferably, the valve comprises a second stabilisation membrane arrangedsnap-fitted into the secondary volume for splitting it into an auxiliaryvolume and an intermediate volume. The intermediate volume is comprisedbetween the first stabilisation membrane and the second stabilisationmembrane for containing a fluid at a pressure substantially equal to theatmospheric pressure value.

Advantageously, the stabilisation membranes allow defining anintermediate volume in which there is no fluid, but only air at apressure equal to the atmospheric pressure. In this way, pressing forcesare only applied to the first stabilisation membrane by the fluid comingfrom the outlet passage, avoiding compromising its operation.

According to one aspect of the invention, the actuating means comprisesan actuating shaft extending along the movement direction at least fromthe auxiliary volume towards an operating end arranged in the mainvolume.

Preferably, the actuating means comprises a tubular element extendingalong the movement direction within which the actuating shaft isinserted for placing the main volume in fluid connection with theauxiliary volume.

Advantageously, the tubular element allows the movement of the actuatingshaft along the movement direction. However, this tubular element allowsthe passage of part of the fluid coming from the inlet passage towardsthe secondary volume. The presence of the second stabilisation membraneallows confining this amount of fluid in the auxiliary volume,preventing it from flowing towards the intermediate volume where itwould come into contact with the first stabilisation membrane.

According to one aspect of the invention, on the side facing towards thesecondary volume of the connection portion a flat surface is presentwhich is orthogonal to the axis of extension exposed to the pressure ofthe fluid so as to apply a thrust pressure on the shutter towards theclosed position. For example, in the case in which the secondstabilisation membrane is damaged, the presence of a flat surface ofseparation between the connecting portion of the membrane and the fixedportion of the valve allows the fluid to infiltrate therein. As afunction of the pressure of the fluid, the first stabilisation membrane(kept firmly in its position by its connecting portion constrained tothe valve and by the presence of the elastic element) is movable alongthe movement direction in such a way as to apply a pressing force on theshutter via the elastic element that keeps it in the closed position.

Preferably, the connecting portion has a blind cavity defined in part bythe side of the first stabilisation membrane facing towards thesecondary volume for containing a quantity of fluid infiltrated betweenthe first stabilisation membrane and the fixed portion so as to apply athrust pressure on the shutter towards the closed position.

The fluid infiltrated between the membrane and the fixed portion isadvantageously stored in the blind cavity in order to apply thenecessary pressing force on the shutter to keep it in the closedposition.

According to one aspect of the invention, the valve comprises a rigidcover of the stabilisation membrane interposed between the stabilisationmembrane itself and the elastic element. The rigid cover is superposedon the stabilisation membrane and is movable along the movementdirection as a function of the quantity of fluid stored in the blindcavity to assist the elastic element in maintaining the shutter in theclosed position.

Advantageously, as the rigid cover is not constrained to anything butmerely superposed on the membrane and interposed with the elasticelement, it provides protection to the first stabilisation membrane andis able to more efficiently apply the pressing force on the shutterinduced by the quantity of fluid infiltrated into the blind cavity.

According to another aspect of the invention, the actuating shaft passesthrough the second stabilisation membrane, the first stabilisationmembrane, the rigid cover and the shutter.

According to a further aspect of the invention, the valve comprisesmagnetic activation means operatively active on a movement end of theactuating shaft opposite the operating end for moving said actuatingshaft along the movement direction.

A valve comprises two stages, wherein at least a second stage has atleast any one of the features previously introduced.

Preferably, a first stage comprises a further shutter arranged in theprimary volume and movable along the movement direction between a flowposition and a locked position. In the flow position the further shutterallows the passage of the fluid towards the shutter, while in the lockedposition the further shutter prevents the passage of the fluid.

According to one aspect of the invention, the valve comprises a tertiaryvolume interposed between the shutter and the further shutter. Thistertiary volume has an inlet opening in fluid communication with theinlet passage and an outlet opening in fluid communication with theoutlet passage. The shutter abuts on the outlet opening when it is inthe closed position, while the further shutter abuts on the inletopening when it is in the locked position.

Preferably, the actuating shaft is common to both of the shutters and isconfigured to move the shutter and the further shutter. The actuatingshaft is inserted in the tertiary volume so that the operating endinteracts with the further shutter.

Advantageously, the movement member is configured to be able to move theshutter and the further shutter. Each shutter is independent withrespect to the other, so as to be able to obtain every possibleconfiguration of the positioning of the shutters according to need.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional features and advantages of the present invention will becomemore apparent from an approximate, and thus non-limiting, description ofa preferred, but non-exclusive embodiment of a valve for fluids,preferably for gases, as illustrated in the appended drawings, in which:

FIG. 1 shows a front view of a valve for fluids;

FIG. 2 shows a front view of a section along a transverse plane, of afirst embodiment of the valve for fluids;

FIG. 3 shows a front view of a section along a transverse plane, of asecond embodiment of the valve for fluids;

FIGS. 4 and 5 show a side view of a section along a transverse plane, asthe pressure induced by the fluid acts on the membranes and on theshutter of the valve during back pressure tests;

FIG. 6 shows a side view of a section along a transverse plane, as thepressure induced by the fluid acts on the membranes and on the shutterof the valve during the test in which the second stabilisation membraneis removed and with a flow of fluid from the inlet passage towards theoutlet;

FIG. 7 shows a front view of an enlargement with some parts removed tobetter highlight others, of a portion of the valve for fluids sectionedalong a transverse plane.

With reference to the drawings, they serve solely to illustrateembodiments of the invention with the aim of better clarifying, incombination with the description, the inventive principles at the basisof the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

The present invention relates to a valve for fluids, preferably forgases.

With reference to the figures, a valve for fluids, preferably for gases,has been generically indicated with the number 1.

The other numerical references refer to technical features of theinvention which, barring indications otherwise or evident structuralincompatibilities, the person skilled in the art will know how to applyto all the variant embodiments described.

Any modifications or variants which, in the light of the description,are evident to the person skilled in the art, must be considered to fallwithin the scope of protection established by the present invention,according to considerations of technical equivalence.

FIG. 1 shows a valve 1 for fluids, preferably for gases, comprising twoconsecutive and independent stages, which manage the passage of thepredetermined fluid through the valve 1.

The second stage of the valve 1, as shown in FIG. 2, comprises an inletpassage 2 and an outlet passage 3 for the fluid between which a primaryvolume V is defined, a shutter 4 interposed between these passages andmovable along a movement direction L between an open position and aclosed position. In the open position the shutter 4 allows the flow ofthe gas from the inlet passage 2 to the outlet passage 3 along a slidingdirection, while in the closed position the shutter prevents the flow ofthe gas.

Furthermore, the second stage comprises actuating means 5 movable alongthe movement direction L and operatively active on the shutter 4 formoving the shutter into the open position, and a first stabilisationmembrane 6 interposed between the shutter 4 and a fixed portion 7 of thevalve 1 in such a way as to expose an active wall 8 to the fluid presentbetween the outlet passage 3 and the shutter 4.

Specifically, as can be better seen in FIG. 7, the active wall 8 has anouter surface 9 arranged at the outlet passage 3 and facing towards arear surface 10 of the shutter 4, which is opposite the inlet passage 2of the valve 1. The outer surface 9 is conformed so that the force dueto the pressure of the fluid acting on the active wall 8 is less thanthe force due to the pressure of the fluid acting on the rear surface 10of the shutter 4, so as to prevent the pressurised fluid from being ableto open the shutter 4 when the latter is in the closed position and thevalve 1 is at the same time in a back pressure condition, i.e. acondition in which the fluid flows from the outlet passage 3 towards theinlet passage 2.

In addition, the second stage of the valve 1 comprises a secondaryvolume W arranged along the movement direction L and separated from theprimary volume V by the first stabilisation membrane 6.

Advantageously, the shutter 4 has a through hole configured to put thesecondary volume W in fluid connection with the inlet passage 2 when thesame shutter 4 is in the closed or open position and when the valve 1 isunder a normal pressure condition. Even more advantageously, theactuating means 5 comprises an interstitial space 25 in fluidcommunication with the through hole to define the passage of the fluidtowards the secondary volume W.

FIG. 2 and FIG. 3 also show the first stage of the valve 1, whichcomprises a further shutter 22 interposed between the passages 2,3 andmovable along the movement direction L between a flow position and alocked position. In the flow position the further shutter 22 allows thepassage of the gas towards the shutter 4, while in the locked positionit prevents this passage of gas. Further actuating means 30 areconnected to the further shutter 22 which are controlled by anelectromagnet 31 arranged in a suitable box-shaped body 32 partiallyinserted in the valve 1. The box-shaped body 32 is arranged along themovement direction L outside the valve 1.

A tertiary volume M is defined between the shutter 4 and the furthershutter 22 that is part of the primary volume V, which has an inletopening 23 in fluid communication with the inlet passage 2 and an outletopening 24 in fluid communication with the outlet passage 3. In thisway, the shutter 4 abuts on the outlet opening 24 when it is in theclosed position, while the further shutter 22 abuts on the inlet opening23 when it is in the locked position.

The tertiary volume M extends along the movement direction L, so thatthe inlet opening 23 and the outlet opening 24 are arrangedtransversally with respect to the inlet passage 2 and the outlet passage3. Consequently, the flow of the gas does not follow a linear path whenpassing from the inlet passage 2 to the outlet passage 3.

According to one aspect of the invention, in normal use conditions ofthe valve 1, the gas is able to flow through the primary volume V whenthe shutter 4 is in the open position and the further shutter 22 is inthe flow position.

However, when the further shutter 22 abuts in the open position, part ofthe gas is able to reach the secondary volume W.

According to one aspect of the invention shown in FIG. 2, the valve 1comprises a second stabilisation membrane 15 arranged snap-fitted intothe secondary volume W for splitting it into an auxiliary volume U andan intermediate volume Y. More precisely, therefore, the gas is able toreach the auxiliary volume U.

In this way, the intermediate volume Y, defined between the firststabilisation membrane 6 and the second stabilisation membrane 15,contains only air at a pressure equal to the atmospheric pressure.According to this aspect of the invention, the tubular element 17 putsthe primary volume V in fluid communication with the auxiliary volume U.

Consequently, under normal conditions, the first stabilisation membrane6 receives stresses only on its outer surface 9, i.e. that turnedtowards the outlet passage 3.

According to one aspect of the invention, the actuating means 5 extendsalong an axis of extension A parallel to the movement direction L.

More precisely, the actuating means 5 comprises an actuating shaft 16and a tubular element 17, both extending along the movement direction Lbetween the main volume V and the secondary volume W.

Even more precisely, the tubular element 17 is hollow to allow theinsertion of the actuating shaft 16. In order to allow the sliding, thetransverse section of the actuating shaft 16 is equal to, or preferablyless than, the transverse section of the tubular element 17. In thisway, when the further shutter 22 is in the flow position, the tubularelement 17 puts the primary volume V in fluid communication with thesecondary volume W.

In other words, between the actuating shaft 16 and the tubular element17 an interstitial space 25 is defined, thanks to which the gas flowstowards the secondary volume W.

Advantageously, when the shutter 4 is in the closed position and at thesame time the gas flows between the inlet passage 2 and the outletpassage 3, the interstitial space 25 allows obtaining a balancing of thepressures induced on the shutter 4 and a second stabilisation membrane15 arranged snap-fitted in the secondary volume W. In particular, theinterstitial space 25 allows part of the gas to flow from the inletpassage 2 toward the secondary volume W, filling it, and causing athrust pressure on the second stabilisation membrane 15 equal andopposite the thrust pressure normally induced on the shutter 4 in orderto counteract it.

According to a preferred aspect of the invention, the actuating shaft 16is common to both shutters 4,22 and is configured to move themindependently with respect to one another.

Specifically, the actuating shaft 16 passes through the secondstabilisation membrane 15, the first stabilisation membrane 6 and theshutter 4.

More precisely, the actuating shaft 16, inserted through the tubularelement 17, extends at least from the secondary volume W towards anoperating end arranged in the main volume V. This operating end is usedto move the further shutter 22 from the flow position to the lockedposition.

While the actuating shaft 16 moves the shutter 4 in the open position,an elastic element 13 is interposed between the fixed portion 7 of thevalve 1 and the shutter 4 to move it in the closed position. Preferably,the first stabilisation membrane 6 has a connecting portion 14 arrangedbetween the elastic element 13 and the fixed portion 7 of the valve 1.

Similarly, the actuating shaft 16 moves the further shutter 22 in theflow position, while a spring is able to reposition it in the lockedposition.

The movement of the actuating means 5 along the movement direction L isensured by the magnetic activation means 21 operatively active on oneend of the movement of the actuating shaft 16 opposite the operatingend.

Specifically, the magnetic activation means 21 comprises anelectromagnet 26 and a magnetic body 27 connected to the movement end ofthe actuating shaft 16, which is made of a magnetic and/or ferromagneticmaterial. The electromagnet 26, integral with respect to the valve 1, iscapable of generating a magnetic field such as to interact with themagnetic body 27 to move it and/or keep it in position along themovement direction L.

Alternatively, according to a different aspect of the invention notshown in the appended figures, the electromagnet 26 is connected to themovement end of the actuating shaft 16 (preferably by means of aconnection of the voice-coil type), while the magnetic body is rigidlyintegral with the valve 1, in this way the magnetic field produced bythe electromagnet 26 will directly move the latter along the movementdirection L.

As shown in FIGS. 4 to 6, in the back-pressure condition, i.e. the flowof the gas from the outlet passage 3 towards the inlet passage 2, thepressing force that the gas exerts on the membrane increases withrespect to normal conditions. The valve 1, under this condition ofgreater stress, must be able to ensure an isolation of the outletpassage 3 from the rest of the primary volume V.

To this end, the first stabilisation membrane 6 comprises a sleeve 12arranged adjacent to at least part of the actuating means 5 for beingconstrained to the latter at the shutter 4 and define a physicalseparation of the main volume V when the shutter 4 is in the closedposition. Specifically, the stabilisation membrane 6 surrounds the axisof extension A of the actuating means 5 and lies on a planesubstantially orthogonal to the axis itself.

According to a first aspect of the valve 1 shown in FIG. 2, the activewall 8 of the first stabilisation membrane 6 is preferably, but notnecessarily, inclined with respect to the axis of extension A towards acommon portion of the shutter 4, assuming the shape of a cone or atruncated cone.

Preferably, the first stabilisation membrane 6 is of the bellows type tofollow the movement of the actuating means 5 along the movementdirection L. More precisely, the stabilisation membrane 6 has a bellowsportion arranged between the active wall 8 and the connecting portion14.

According to a different aspect of the invention that can be seen inFIG. 3, the active wall 8 has a concavity 11 that extends away from theshutter 4 substantially along the movement direction L.

FIG. 6 shows the valve 1 for fluids in which there is no secondstabilisation membrane 1, in order to simulate the possibility that thismembrane is malfunctioning, not ensuring a clear separation of thesecondary volume W.

In this case, therefore, the gas present in the auxiliary volume Uinfiltrates into the intermediate volume Y, inducing a significantpressure on an inner surface of the first stabilisation membrane 6.

According to one aspect of the invention, on the side of the connectingportion 14 facing towards the secondary volume W, a flat surface 18 ispresent that abuts on the fixed portion 7 of the valve 1. The flatsurface 18 is orthogonal with respect to the axis of extension A and isexposed to the pressure of the gas in such a way as to apply a thrustpressure on the shutter 4 towards the closed position.

In other words, the gas of the secondary volume W is able to infiltratealong the flat surface 18, between the fixed portion 7 and theconnecting portion 14, to generate a pressure on the stabilisationmembrane 6 at the connecting portion 14, and therefore cause adeformation of the latter. In this way the pressure induced by theinfiltrated gas along the flat surface 18 moves the rigid cover 20resting on the stabilisation membrane 6 to increase the actual loadapplied by the elastic element 13 on the shutter 4. Specifically, as canbe better seen in FIG. 7, the area of infiltration of the connectingportion 14 at the flat surface 18 can be deformed thanks to thelightened conformation present on the peripheral part of thestabilisation membrane 6 itself.

Preferably, the connecting portion 14 has a blind cavity 19 whichextends towards the primary volume V.

More precisely, the blind cavity 19 is substantially shaped like arecess that substantially propagates towards the rigid cover 20.

Consequently, the blind cavity 19 is able to contain a determined amountof infiltrated gas between the stabilisation membrane 6 and the fixedportion 7 so as to apply the thrust pressure on the shutter 4 towardsthe closed position.

According to the aspect just described, the gas in the intermediatevolume Y is advantageously directed between the connecting portion 14 ofthe first stabilisation membrane 6 and the fixed portion 7 of the valve1, more precisely in the specially afforded blind cavity 19. In thisway, the pressure produced by the gas from the secondary volume Wtowards the primary volume V, which would tend to move the membranealong the movement direction L towards the primary volume V, istransmitted to the elastic element 13, which in turn imparts a pressureon the rear surface 10 of the shutter 4, keeping it in the closedposition.

Preferably, the valve 1 comprises a rigid cover 20 of the firststabilisation membrane 6, which is interposed between the firststabilisation membrane 6 itself and the elastic element 13.

The rigid cover 16 is superposed on the first stabilisation membrane 6in such a way as to be movable along the movement direction L as afunction of the quantity of fluid stored in the blind cavity 19.

Advantageously, the rigid cover 20, pushed by the gas in theintermediate volume Y through the first stabilisation membrane 6, iscapable of imparting a pressing force on the elastic element 13 to keepthe shutter 4 in the closed position. At the same time, the rigid cover20 is capable of providing a protection to the membrane against thedamage caused during its use, such as for example the friction producedby the elastic element 13.

With regard to an operating example of the valve 1 for fluids,preferably for gases, it derives directly from what is described abovewhich is referred to below.

Under normal conditions, the further shutter 22 is in the lockedposition due to the further actuating means 30 preferably through aspring interposed between the box-shaped body 32 and the further shutter22.

In this condition the gas is able to flow from the inlet passage 2 onlyto the portion of the inner volume V comprised between the furthershutter 22 and the entrance of the inlet passage 2.

The activation of the actuating means 5 allows the movement of theactuating shaft 16 along the movement direction L. When the operatingend of the actuating shaft 16 collides with the further shutter 22, thelatter moves from the locked position towards the flow position alongthe movement direction L. At a certain distance from the box-shaped body32, the field lines generated by the electromagnet 31 of the furtheractuating means 30 are able to interact with a magnetic and/orferromagnetic portion of the further shutter 22 so as to cause it tocomplete its stroke, up to abutting in the flow position in which it iskept.

Advantageously, the actuating shaft 16 passes through the shutter 4thanks to a suitable cavity present on the latter. In this way, thismethod does not interfere in any way with the positioning of the shutter4, the shutter 4 and the further shutter 22 are able to be movedindependently from one another.

In this configuration the gas is able to flow to the inside of thetertiary volume M, in which it finds the obstacle of the shutter 4,which is kept in the closed position by the elastic element 13, which isalso generally a spring.

As long as the further shutter 22 is kept in the flow position by theelectromagnet 31, the magnetic activation means 21 is able to move theactuating shaft 16 along the movement direction L, distancing theoperating end from the further shutter 22. In this way, the abutment 29present on the actuating shaft 16 allows the movement by magneticinterference of the shutter 4, dragging it from the closed position tothe open position, counteracting the force exerted by the elasticelement 13 on the shutter 4 to hold it in the closed position.

Preferably, the abutment 29 is a circular ring with a greater section ofthe through cavity of the shutter 24.

In this configuration the gas is able to flow from the tertiary volume Mto the outlet passage 3.

Advantageously, the positioning of the shutter 4 is independent from thepositioning of the further shutter 22, therefore a possibleconfiguration of the valve provides that the further shutter 22 is inthe locked position during the movement of the shutter 4 from the closedposition to the open position, in such a way as to only allow the gascontained in the tertiary volume M to flow outside the valve 1 throughthe outlet passage 3.

Advantageously, the invention allows making the device safer during theback pressure condition, as the first stabilisation membrane is shapedin such a way that the pressure of the gas does not induce a movement ofthe shutter from the closed position to the open position, allowing theflow of the gas itself towards the inlet passage.

1. A valve for fluids, preferably for gases, comprising: an inletpassage and an outlet passage for the fluid within which a primaryvolume is defined; a shutter interposed between the inlet passage andthe outlet passage and movable along a movement direction (L) between anopen position, in which it allows the flow of the fluid from the inletpassage to the outlet passage, and a closed position, in which itprevents the flow of fluid; an actuating means movable along themovement direction (L) and operatively active on the shutter for movingthe shutter itself into the open position; a first stabilizationmembrane interposed between the shutter and a fixed portion of thevalve; said first stabilization membrane being conformed so as to exposean active wall to the fluid present between the outlet passage and theshutter; said active wall having an outer surface arranged at the outletpassage and facing towards a rear surface of the shutter opposite theinlet passage; said outer surface being conformed so that the pressureof the fluid acting on said active wall generates a force that is lowerthan the force generated by the pressure of the fluid acting on the rearsurface of the shutter so as to prevent the fluid opening the shutter,when the shutter is in the closed position and when the valve is in aback pressure condition, in which the fluid flows from the outletpassage to the inlet passage; it comprises a secondary volume (W)arranged along the movement direction (L) and separated from the primaryvolume (V) by the first stabilization membrane; said shutter having athrough hole configured to put said secondary volume (W) in fluidconnection with said inlet passage when said shutter is in the closedposition and when the valve has a normal pressure condition; saidactuating means comprising an interstitial space in fluid communicationwith said through hole for the passage of the fluid towards saidsecondary volume (W).
 2. The valve according to claim 1, wherein theactuating means extends along an axis of extension (A) parallel to themovement direction (L).
 3. The valve according to claim 2, wherein thefirst stabilization membrane surrounds said axis of extension (A); saidfirst stabilization membrane lying on a substantially orthogonal planeto the axis of extension (A).
 4. The valve according to claim 3, whereinthe active wall is inclined with respect to the axis of extension (A)moving towards the shutter.
 5. The valve according to claim 4, whereinthe first stabilization membrane is of the bellows type for followingthe movement of the actuating means along the movement direction (L). 6.The valve according to claim 3, wherein the active wall has a concavityextending away from the shutter substantially along the movementdirection (L).
 7. The valve according to claim 1, wherein the firststabilization membrane comprises a sleeve connected to the active walland arranged adjacent to at least part of the actuating means for beingconstrained to the latter at the shutter.
 8. The valve according toclaim 1, comprising an elastic element interposed between the fixedportion of the valve and the shutter for moving and/or keeping theshutter in the closed position.
 9. The valve according to claim 8,wherein the first stabilization membrane has a connecting portionarranged between the elastic element and the fixed portion.
 10. Thevalve according to claim 1, comprising a second stabilization membranearranged snap-fitted into the secondary volume (W) for splitting it intoan auxiliary volume (U) and an intermediate volume (Y); saidintermediate volume (Y) being comprised between the first stabilizationmembrane and the second stabilization membrane for containing a fluid ata pressure substantially equal to the atmospheric pressure value. 11.The valve according to claim 10, wherein said interstitial space andsaid through hole are configured to put said inlet passage in fluidcommunication with said auxiliary volume (U) so that the fluid undernormal pressure conditions acts on the second stabilization membrane tocounterbalance the pressure induced on the shutter.
 12. The valveaccording to claim 10, wherein the actuating means comprises anactuating shaft extending along the movement direction (L) at least fromthe auxiliary volume (U) towards an operating end arranged in the mainvolume (V).
 13. The valve according to claim 12, wherein the actuatingmeans comprises a tubular element extending along the movement direction(L) within which the actuating shaft (16) is inserted for placing themain volume (V) in fluid connection with the auxiliary volume (U). 14.The valve according to claim 9, wherein the connecting portion on theside facing towards the secondary volume (W) has a flat surfaceorthogonal with respect to the axis of extension (A) exposed to thepressure of the fluid so as to apply a thrust pressure on the shuttertowards the closed position.
 15. The valve according to claim 14,wherein the connecting portion has a blind cavity defined in part by theside of the first stabilization membrane facing towards the secondaryvolume (W) for containing a quantity of fluid infiltrated between thefirst stabilization membrane and the fixed portion so as to apply athrust pressure on the shutter towards the closed position.
 16. Thevalve according to claim 15, comprising a rigid cover of the firststabilization membrane interposed between the first stabilizationmembrane itself and the elastic element; said rigid cover beingsuperposed on the first stabilization membrane and being movable alongthe movement direction (L) as a function of the quantity of fluid storedin the blind cavity to assist the elastic element in maintaining theshutter in the closed position.
 17. The valve according to claim 16,comprising a second stabilization membrane arranged snap-fitted into thesecondary volume (W) for splitting it into an auxiliary volume (U) andan intermediate volume (Y); said intermediate volume (Y) being comprisedbetween the first stabilization membrane and the second stabilizationmembrane for containing a fluid at a pressure substantially equal to theatmospheric pressure value, wherein the actuating means comprises anactuating shaft extending along the movement direction (L) at least fromthe auxiliary volume (U) towards an operating end arranged in the mainvolume (V), and wherein the actuating shaft passes through the secondstabilization membrane, the first stabilization membrane, the rigidcover and the shutter.
 18. The valve according to claim 12 comprising amagnetic activation means operatively active on a movement end of theactuating shaft opposite the operating end for moving said actuatingshaft along the movement direction (L).
 19. A valve comprising twostages, wherein at least a second stage comprises the characteristics ofthe valve according to claim
 1. 20. The valve according to claim 19,wherein a first stage comprises a further shutter arranged in theprimary volume (V) and movable along the movement direction (L) betweena flow position, in which it allows the passage of fluid towards theshutter, and a locked position, in which it prevents the passage offluid.
 21. The valve according to claim 20, comprising a tertiary volume(M) interposed between the shutter and further shutter having an inletopening in fluid communication with the inlet passage and an outletopening in fluid communication with the outlet passage; said shutterabutting on said outlet opening when in the closed position; saidfurther shutter abutting on said inlet opening when in the lockedposition.
 22. The valve according to claim 21, wherein the actuatingshaft is common to both of the shutters and is configured to move theshutter and the further shutter; said actuating shaft being inserted inthe intermediate volume (M) so that the operating end interacts with thefurther shutter.